In many industrial environments various types of liquid and gas mixtures are formed which require separation at a later point in the manufacturing procedure. One particular area in which this occurs is in connection with industrial dewatering processes.
Two particular industrial applications for dewatering processes are in the textile industry and in the papermaking industry. Papermaking machinery, particularly the wet end of the machinery, is commonly used to dewater wet webs such as papermaker's felts. Suction box and suction pipe systems are used with an appropriate vacuum source to draw air through the felt and collect water within the pipe which is then directed to a separation station for separation of the water and air.
Currently used systems which operate effectively present other concerns. They are generally large and unwieldy causing the manufacturer to utilize large manufacturing areas for the separation process. In one effective system of separator technology presently in use, a suction pipe is placed beneath a moving, wet web, and has the function of mechanically sucking water from the web. The water ladened air passes into the side of a centrifugal separator. The spinning action in the separator separates the water from the air. The water runs down a funnel shaped floor of the centrifugal separator and into an elongated standpipe. The extremely elongated standpipe extends into a sealed pit in the basement of the manufacturing facility. The relatively dry air leaves the centrifugal separator near the top and passes through a blower exhauster or vacuum pump which exhausts to atmosphere. The purpose of the blower or vacuum pump is to cause the air motion through the system. The key feature in that type of system is the standpipe with its associated seal pit. Typically, a distance of 15 feet from the bottom of the separator to the floor of the basement is needed and this could increase in certain environments up to 30 feet. The purpose for the standpipe and seal pit is to trap the vacuum in the centrifugal separator and suction pipe, while allowing water to be removed from the system. The height of the water in the standpipe determined by the vacuum level in the system. Clearly, improvement is needed for consolidating the system so that there is an advantageous savings in manufacturing space and in equipment cost.
The ideal answer is to utilize a basementless separator system. The paper industry currently has a system of that type in use. In that system, the water from the centrifugal separator dumps directly into a holding tank. A level sensor, usually a mechanical float type, senses the level of the water in the tank. A centrifugal pump removes water from the bottom of the tank, and sends it to the drain through a valve. The position of the valve is controlled by the height of the water, as sensed by the level detector. Thus, the height of the water and the holding tank is held relatively constant. In its current application in the paper industry, the linear output liquid level sensors can clog up with paper pulp from the water. Also, a pump is needed, which runs 100 percent of the time. Not only does this result in an inefficient system in the paper industry but it is completely unacceptable for use in dewatering procedures in other industries such as the textile industry. The position controlled valve on the output of the pump is normally operating in a partly opened condition. Due to the high fiber content in the water the partially opened valve can rapidly become plugged in fiber. It also becomes very difficult to get linear output liquid level sensors which are insensitive to fiber and debris in the water.